What is involved with installing an Alpine HU to a Mach 460 system?

[GDawg]

I just bought an Alpine CDA-9855 to replace my Mach 460 HU. I know I'll need the Scosche OEM Amplifier Adapter. I'm going to buy that from Crutchfield. I bought the HU from Best Buy but don't feel comfortable with them doing the install.

How hard is it to do myself? Do instructions come with the adapter?

tia